Slaxl:We've only been detecting planets for the last 20 years or so, and of that the vast majority have been massive worlds big enough to detect, yet now we're making assumptions based on the frequency of asteroid belts, which I am amazed to learn are detectable at all. Can we really detect asteroid belts? If so, how?

You can tell the older systems by the Orions hitched to their asteroid belts, which was the style at the time.